I started on 50mg for pac's and pvc's.. side effects the first weak were horrible.. slowness, feeling as if I was a train slowing down, tired, and weak.. but after a week all the symtoms went away. I was told to up the medication to 100mg, so I have to go through all this again another wek until I get use to it. One of the side effects that is most annoying is heavy chest... but that goes away after a couple hours. No depression, no problems with sex, it really helps in keeping the palps away.